The touch-tone style telephone call transmitter is enjoying increased, favorable acceptance by telephone subscribers. Call transmitters employing touch-tone principles are described in numerous patents including U.S. Pat. Nos. 3,109,071, 3,123,676, 3,274,345, 3,316,357 and 3,479,470 -- the latter two being based on divisional applications of U.S. Pat. No. 3,274,345. The basic principles of operation of the standard touch-tone unit are set out in the U.S. Pat. No. 3,274,345 at Column I, line 32 through Column II, line 5.
Many of the advantages of the pushbutton type dial assembly are pointed out in U.S. Pat. 3,076,059. An advantage of particular note with regard to the touch-tone assembly is the fact that it provides more efficient use of transmission facilities with the reduction of calling time, as compared with a standard rotary dial, by approximately one-half. The latter attribute is extremely attractive since a material saving in telephone central office common equipment is possible.
A psychological feature of the touch-tone assembly, in this day and age when everyone appears to be in a hurry, is the relative rapidity compared with the rotary dial system with which one can place a call.
Because of this psychological advantage enjoyed by the touch-tone concept, if it were possible to convert the standard rotary dial systems to the touch-tone dial configuration the enhanced marketability of such an item would appear to be significant. The idea would be to remove the present assembly, i.e., the rotary dial assembly, from the standard telephone subset and to place therein a touch-tone like assembly which phychologically speaking appeals to the subscriber in the same manner as an actual touch-tone assembly. Of course, from an operational point of view a conversion must take place, preferably within the touch-tone like assembly which replaces the rotary dial assembly. This conversion hereinafter referred to as outpulsing, permits pushbutton dialing with a suitable loop-disconnect output compatible to the rotary dial output as is well known to those in the telephone art. Because of the difference in the dial times associated with the touch-tone dial and the rotary dial system, it is apparent that a memory device would have to be provided which would store the number as it is dialed and then feed it to the telephone transmission lines in the proper sequence and pulse form.
Given the increased subscriber acceptance of the touch-tone arrangement for telephone subsets, it is recognized that by increasing the ancillary functions that a telephone provides, a telephone equipment supplier can further enhance the marketability of his product. These ancillary functions might include a repertory dial function which can provide electronic storage of up to ten frequently called numbers of 12 or 16 digits each, all of which can be stored, erased or changed by simple keying means employing the telephone buttons. This enables the subset operator to select a particular stored number through proper keying leaving the transmitter itself to "place" that number once it is identified by the subset operator.
An additional function which can be included within the ancillary function area is the so-called "Toll Restrictor" function. Generally, this function is provided, typically, in business office exchange systems where it is desirable to prevent the dialing of area code calls from all but a few selected subsets. It does this by recognizing that an area code call is being dialed, as opposed to the first three numbers of a local exchange. When it detects this occurrence the toll restrictor circuitry is designed to cut off the corresponding subset connection -- thus interrupting the call.
Also, functions not directly related to the telephone art but which provide subscriber convenience such as an electronic calculator, are desirable additions.
Until now, the outpulsing function and the various ancillary functions where desired had to be packaged external to a particular telephone subset. The additional packaging costs and logistic problems oftentimes offset the advantages to be gained thereby such that the equipment manufacturer would not contemplate even providing these functions or, if he did, less than enthusiastic customer acceptance was found due to "excessive " cost.
Recent developments in the art of electronic circuit fabrication, particularly microminiturization and more particularly large scale integration (LSI), have added a new dimension to electronic circuit packaging generally. Particularly, it has enabled telephone packaging engineers and designers to contemplate unique packaging techniques whereby the outpulsing and ancillary functions could be provided in a manner where the logistic's problems and cost to the subscriber would be kept at a minimum.
It is a primary object of this invention to provide a dial assembly having a touch-tone like dial face which is expanded to include additional ancillary functions heretofore packaged separate to the basic telephone subset.
It is another object of this invention to provide touch-tone telephone dial assembly which can provide certain ancillary functions and do so within the volume outline of present dial assemblies.
It is yet another object of this invention to provide a touch-tone like dial assembly which can be readily substituted for the standard rotary dial assembly without any modification to standard telephone subsets.
It is still another object of this invention to provide a touch-tone like dial assembly which includes means for providing a plurality of mounting configurations which enable the basic assembly to be utilized in a variety of subset configurations.
It is another object of this invention to provide an additional plane of switching within a telephone subset which expands the potential of heretofore standard systems.
It is a further object of this invention to utilize the latest advances in microcircuit development, including LSI development, with or without the third plane of switching, to expand the number and type of ancillary functions which can be provided within a subset.